The present invention relates to a distributed processing system to which a plurality of image information supplying apparatuses such as a personal computer (which will be hereinafter referred to as a PCxe2x80x94Personal Computerxe2x80x94) or a digital camera and a plurality of image forming apparatuses such as a color plain paper copy machine (which will be hereinafter referred to as a PPCxe2x80x94Plane Paper Copy machinexe2x80x94) or a printer are connected and which is provided with a distributed processing server for executing load distribution of jobs, and more particularly to a distributed processing system capable of efficiently forming images at a high speed even if color reproduction capabilities of respective image forming apparatuses connected to this system are different from each other.
In regard to a problem of management of colors in the field of image forming techniques such as printing or copying, a property of human visual sense to colors must be first taken into consideration. xe2x80x9cColor management!xe2x80x9d by Toru Kasai describes this management of colors (color management) as follows.
xe2x80x9cA human eye has a cone cell sensitive to red, green and blue. Quantifying the stimulation given to each cell results in XYZ.
The value of XYZ can be used to represent all the colors seen by a human being as numerical values, but such values vary in accordance with a change in brightness of illumination light even if the same color is seen. xe2x80x9cA color of an objectxe2x80x9d can not be represented in this way.
Thus, in order to represent a color of an object which can not be indicated by XYZ, a numerical quantity of lower case xy is used. This is a value which performs notation by using a ratio which becomes 1 by summing up XYZ and in which z is omitted. When a graph is made by using this numerical value, a CIE xy chromaticity diagram can be obtained.
With the CIE xy chromaticity diagram, it can be known that what kind of color rendering range (capability for reproducing colors) an apparatus for representing colors has. For example, a monitor and an offset printer have different color rendering ranges. It can be said that color matching by using a color management system (CMS) is a function for conveniently making these different color rendering ranges consistent with each other.xe2x80x9d
As similar to the above-described CIE xy chromaticity diagram, the color range of visible light rays which can be reproduced by a human eye greatly exceeds a region which can be reproduced by an RGB (red-Red, green-Green, blue-Blue) model or a CMYK (cyan-Cyan, magenta-Magenta, yellow-Yellow, black-Black) model. The region of colors which can be reproduced by the RGB model and the CMYK model do not completely coincide with each other. Since the RGB and the CMYK are not completely compatible with each other, different colors may be reproduced at an output device if these models remain unchanged.
For the purpose of adjusting a difference between output devices, there is adopted an interface for a color management system (ICM) which is called xe2x80x9cICMxe2x80x9d in xe2x80x9cWindows 98xe2x80x9d and called xe2x80x9cColorSyncxe2x80x9d in xe2x80x9cMacOS.xe2x80x9d In this ICM, there is used a standard format called the xe2x80x9cICC profilexe2x80x9d proposed by the international color consortium (ICCxe2x80x94International Color Consortiumxe2x80x94). The ICC profile is a table indicating vales for conversion of a color model dependent on an apparatus and a color model independent on an apparatus. By using the ICC profile, the application reconverts a color processed in various input/output devices in order to transfer it to a different input/output device through a relay point with a device-dependent color space as a reference being used as a relay for conversion, thereby completing transfer of the color. Therefore, it is possible to absorb the inconformity of the reproducible color regions between the RGB model and the CMYK model to some degree.
Recently, a color printer of one-drum mode using an intermediate transfer medium has been spread, and the color/monochrome mixed printing environment has been regularized. The one-drum type color printer using the intermediate transfer medium, a print completion timing of a monochrome page is different from that of a color page because of the mechanism thereof. In case of the color printing, since toners for four colors of CMYK (cyan, magenta, yellow and black) are mounted for each one rotation, the drum makes four rotations until the printing is completed. In case of the monochrome printing, only one color of K (black) is used, and hence one revolution can suffice the drum until the printing is completed. According to this one-drum mode, the color printing requires the time which is four-fold of that of the monochrome printing even if the simple calculation is performed.
On the other hand, there is a color printer called a quadruple tandem. In the mechanism of the quadruple tandem, an exposure device and a developer are provided in each of the CMYK and drums for four of the CMYK are linearly arranged. As a result, the color printing can be performed by one pass and, when compared with the one-drum mode, it is characterized in that only one revolution of the drum is enough during the color printing and the color printing can be executed at a high speed.
In the recent circumstances of applications, opportunities for processing colors of, e.g., browsers or PDF files are increasing due to spread of integrative business applications such as Microsoft Word, Excel, PowerPoint and others and spread of the internet, and the environment where colors are processed together with conventional monochrome documents has been realized. For example, this is true to a business document and the like in which a descriptive document is represented in monochrome pages while statistics/graphs are represented in color pages and which deals with them as one document.
Based on these circumstances, a tandem copy/tandem print has been recently proposed. This tandem print/tandem copy mode distributes and processes print jobs/copy jobs in order to shorten the time until the end of the jobs. The structure takes such a form as that at least two color printing devices are connected to the distributed processing server. Performing the distributed processing on a print job generated by a print command from a PC with two copying machines by a client is called the xe2x80x9ctandem print.xe2x80x9d Further, distributing a copy job to be processed in two copying machines is called the xe2x80x9ctandem copy.xe2x80x9d
The conventional job distribution system has distributed a job to color printing devices having different engine characteristics simply every unit of copies. In addition, there is a system which determines a color/monochrome page in a print job in units of a job distribution server, memorizes to which color printer the color page is job-distributed, and transmits a job in a page unit to a printer which is equal to the color printer to which the previous transmission was made when that job has a turn in order to constantly perform output with the same coloring (see Japanese patent application laid-open No. 198533-1998).
However, the above-described prior art has the following problems.
In general, the color printer has a different color rendering range depending on an engine to be used. In cases where the different color printers are connected to the distribution server to carry out the tandem print/copy, their color rendering ranges differ from each other because of different engine characteristics of the respective color printers and, for example, when the distribution server simply carries out the job distribution in units of copies, there occurs a problem such that the colorings of output results are different from each other.
Moreover, in order to solve the above-described problem as in the Japanese patent application laid-open No. 198533-1998, there is a method in which the color printer to which a color page job was job-distributed is previously memorized in order to output with the same coloring and the job is transmitted to the printer equal to the color printer to which the previous transmission was made when that job has a turn in the next time, but this method takes a lot of trouble for a user with merging the color pages and the monochrome pages in order to put output materials in the proper page order after output since the job is distributed every page unit although the same coloring is guaranteed. When the monochrome pages and the color pages are kept together in a measure or when either the color/monochrome pages are extremely small in number, it is not troublesome, but when the color/monochrome pages have the substantially equal number and their pages are alternately mixed up, it takes a lot of trouble with the sorting operation.
Additionally, when the color pages and the monochrome pages are job-distributed simply every page unit, for example, when the number of monochrome pages is extremely small with respect to one print job and the print job is mainly constituted of the color pages, printing of the monochrome pages can be finished extremely faster, but there is a problem such that it takes time until printing of the color pages is completed. If a proportion of the color/monochrome pages with respect to one print job can be analyzed, when a difference between the color pages and the monochrome pages is equal to or above a predetermined value, the job distribution every page unit can be eliminated and replaced with the conventional job distribution in units of copies, thereby shortening the time until printing is completed.
It is an object of the present invention to save labor for a sorting operation after print output and to realize a coloring uniformity of output results between different output devices by compensating a color printer having the engine characteristic of a high color reproduction capability to be matched with a color reproduction space of another color printer having the engine characteristic of a low color reproduction capability, and then distributing a job every copy unit instead of a page unit, when tandem print/copy is carried out between the color printers having different engine characteristics.
Further, there is such a merit that a memory of a client PC is less used by holding a profile of color rendering range information on a printer controller, as compared with a case where an arithmetic operation information profile is held on the client PC. Furthermore, it is another object to save the labor of a user that a profile is installed to the client PC.
Moreover, in the present invention, there is a merit such that a user can obtain an expected output result with respect to a page in which a high picture quality is particularly required among color pages by distributing a job to a color printer having the engine characteristic with the high color reproduction capability every page unit in case of a page in which a high picture quality is required and by distributing a job to a color printer having the engine characteristic with the low color reproduction capability every page unit in case of any other pages. However, the sorting operation is produced after the print output in this method.
To achieve the above-mentioned aim, a distributed processing system for an image forming apparatus according to a basic structure of the present invention comprises a client for supplying an image; a distributed processing server capable of performing distributed processing for one job, which is inputted from the client and which consists of a plurality of pages, by a plurality of image forming apparatuses including at least one color image forming apparatus; and at least two image forming apparatuses which perform image formation of the job on a recording sheet based on a command from the server and which are different from each other in color image formation processing capability, the distributed processing server comprising a storage portion for previously storing data concerning the respective image formation processing capabilities including color reproduction capabilities in the plurality of image forming apparatuses; a job analysis potion for analyzing contents of the job supplied from the client and an image formation request of the client concerning this job; a comparison portion for comparing a result of analysis by the job analysis portion with the data concerning capabilities of the plurality of image forming apparatuses stored in the storage portion; a correcting portion for correcting the image formation contents of a job to be supplied to the image forming apparatus having a high image formation capability based on a result of comparison by the comparison portion in accordance with the capability of the image forming apparatus having a low image formation processing capability to generate an image formation command for carrying out image formation with the corrected contents; and an output portion for distributing and outputting the job corrected by the correction portion to each of the plurality of image forming apparatuses, the image forming apparatus having the high image formation capability among the plurality of image forming apparatuses comprising an interpretation portion for interpreting the image formation command added to the corrected job supplied from the distributed processing server; and an execution portion for executing image formation in accordance with the interpreted contents.
Additionally, in the distributed processing system for the image forming apparatus according to the above-described basic structure, the plurality of image forming apparatuses may include a plurality of color image forming apparatuses for executing one color image forming job consisting of a plurality of pages inputted from the client, and the distributed processing server may correct a color reproduction space of a job to be supplied to a first color image forming apparatus having the engine characteristic with a high color reproduction capability so as to be matched with a color reproduction space of a second color image forming apparatus having an engine characteristic with a low color reproduction capability and thereafter output it to the first color image forming apparatus.
Moreover, in the distributed processing system for the image forming apparatus according to the above-described basic structure, in the distributed processing server capable of performing distributed processing for one job consisting of a plurality of pages inputted from a client by at least two color image forming apparatuses, color reproduction space information of each color image forming apparatus may be held in the distributed processing server; the distributed processing server may use the held information to correct a color image forming apparatus having an engine characteristic with a high color reproduction capability so as to be matched with the color reproduction space of the color image forming apparatus having an engine characteristic with a low color reproduction, thereby performing image formation.
Further, in the distributed processing system for the image forming apparatus according to the above-described basic structure, a job may be distributed to the color image forming apparatus having an engine characteristic of a high color reproduction capability every page unit to form an image in case of a page in which a high picture quality is required, and a job may be distributed to the image forming apparatus having an engine characteristic with a low color reproduction capability every page unit to form an image in case of any other page.
Additionally, in the distributed processing system for the image forming apparatus according to the above-described base structure, the image forming apparatus having the high image formation processing capability may be constituted of a first image forming apparatus adopting a quadruple tandem color mode; the image forming apparatus having the low image formation processing capability may be constituted of a second image forming apparatus adopting a one-drum mode; a job is distributed to the second image forming apparatus every page unit in case of monochrome pages; and a job is distributed to the first image forming apparatus adopting the quadruple tandem color mode every page unit in case of color pages, thereby subjecting image formation to distributed processing.
As apparent from the above-mentioned structure, in the present invention, a user can have a wide range of selection and a service that a user expects can be satisfied by providing means for enabling by a control panel attached to a printer driver/printer a user to select a method in which xe2x80x9ca color printer having the engine characteristic with the high color reproduction capability is corrected to be matched with a color reproduction space of a color printer having the engine characteristic with the low color reproduction capability and a job is distributed in units of copiesxe2x80x9d and a method in which xe2x80x9ca job is distributed to a color printer having the engine characteristic with the high color reproduction capability every page unit in case of a page in which a high picture quality is required and a job is distributed to a color printer having the engine characteristic with the low color reproduction capability every page unit in case of any other page.xe2x80x9d That is, the present invention includes the structure such that a user can select either the time or the picture quality.
Also, in the present invention, the time until a print output result is obtained can be reduced by a mode by which a job is distributed to a color printer adopting a one-drum mode every page unit in case of a monochrome page and a job is distributed to a color printer adopting a quadruple tandem mode every page unit in case of a color page. This is the reduction in time which can be realized by execution of the job distribution by effectively exploiting the respective engine characteristics such that the color printing is carried out at a high speed in the quadruple tandem mode and the monochrome printing is conducted at a high speed in the one-drum mode.
Additionally, in the present invention, there are provided analyzing means for analyzing how many color pages and how many monochrome pages one print job has and means for switching back to the job distribution in units of copies when a difference between the color pages and the monochrome pages in number is equal to or above a fixed ratio, and a final print output time can be hence minimized by utilizing information of a constitutional ratio of the monochrome/color pages in the print job.